nis/nis_lookup.c

   1 /* Copyright (C) 1997-2021 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3    Contributed by Thorsten Kukuk <kukuk@uni-paderborn.de>, 1997.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, see
  17    <https://www.gnu.org/licenses/>.  */
  18
  19 #include <string.h>
  20 #include <rpcsvc/nis.h>
  21 #include "nis_xdr.h"
  22 #include "nis_intern.h"
  23 #include <libnsl.h>
  24 #include <shlib-compat.h>
  25
  26
  27 nis_result *
  28 nis_lookup (const_nis_name name, const unsigned int flags)
  29 {
  30   nis_result *res = calloc (1, sizeof (nis_result));
  31   struct ns_request req;
  32   nis_name *names;
  33   nis_error status;
  34   int link_first_try = 0;
  35   int count_links = 0;   /* We will follow only 16 links in the deep */
  36   int done = 0;
  37   int name_nr = 0;
  38   nis_name namebuf[2] = {NULL, NULL};
  39
  40   if (res == NULL)
  41     return NULL;
  42
  43   if ((flags & EXPAND_NAME) && (name[strlen (name) - 1] != '.'))
  44     {
  45       names = nis_getnames (name);
  46       if (names == NULL)
  47         {
  48           NIS_RES_STATUS (res) = NIS_NAMEUNREACHABLE;
  49           return res;
  50         }
  51     }
  52   else
  53     {
  54       names = namebuf;
  55       names[0] = (nis_name)name;
  56     }
  57
  58   req.ns_name = names[0];
  59   while (!done)
  60     {
  61       dir_binding bptr;
  62       directory_obj *dir = NULL;
  63       req.ns_object.ns_object_len = 0;
  64       req.ns_object.ns_object_val = NULL;
  65
  66       status = __prepare_niscall (req.ns_name, &dir, &bptr, flags);
  67       if (__glibc_unlikely (status != NIS_SUCCESS))
  68         {
  69           NIS_RES_STATUS (res) = status;
  70           goto out;
  71         }
  72
  73       do
  74         {
  75           static const struct timeval RPCTIMEOUT = {10, 0};
  76           enum clnt_stat result;
  77
  78         again:
  79           result = clnt_call (bptr.clnt, NIS_LOOKUP,
  80                               (xdrproc_t) _xdr_ns_request,
  81                               (caddr_t) &req, (xdrproc_t) _xdr_nis_result,
  82                               (caddr_t) res, RPCTIMEOUT);
  83
  84           if (result != RPC_SUCCESS)
  85             status = NIS_RPCERROR;
  86           else
  87             {
  88               status = NIS_SUCCESS;
  89
  90               if (NIS_RES_STATUS (res) == NIS_SUCCESS)
  91                 {
  92                     if (__type_of (NIS_RES_OBJECT (res)) == NIS_LINK_OBJ
  93                         && (flags & FOLLOW_LINKS)) /* We are following links */
  94                       {
  95                         /* if we hit the link limit, bail */
  96                         if (count_links > NIS_MAXLINKS)
  97                           {
  98                             NIS_RES_STATUS (res) = NIS_LINKNAMEERROR;
  99                             break;
 100                           }
 101                         ++count_links;
 102                         req.ns_name =
 103                           strdupa (NIS_RES_OBJECT (res)->LI_data.li_name);
 104
 105                         /* The following is a non-obvious optimization.  A
 106                            nis_freeresult call would call xdr_free as the
 107                            following code.  But it also would unnecessarily
 108                            free the result structure.  We avoid this here
 109                            along with the necessary tests.  */
 110                         xdr_free ((xdrproc_t) _xdr_nis_result, (char *) res);
 111                         memset (res, '\0', sizeof (*res));
 112
 113                         link_first_try = 1; /* Try at first the old binding */
 114                         goto again;
 115                       }
 116                 }
 117               else
 118                 if (NIS_RES_STATUS (res) == NIS_SYSTEMERROR
 119                     || NIS_RES_STATUS (res) == NIS_NOSUCHNAME
 120                     || NIS_RES_STATUS (res) == NIS_NOT_ME)
 121                   {
 122                     if (link_first_try)
 123                       {
 124                         __nisbind_destroy (&bptr);
 125                         nis_free_directory (dir);
 126                         /* Otherwise __nisfind_server will not do anything.  */
 127                         dir = NULL;
 128
 129                         if (__nisfind_server (req.ns_name, 1, &dir, &bptr,
 130                                               flags & ~MASTER_ONLY)
 131                             != NIS_SUCCESS)
 132                           goto out;
 133                       }
 134                     else
 135                       if (__nisbind_next (&bptr) != NIS_SUCCESS)
 136                         {
 137                           /* No more servers to search.  Try parent.  */
 138                           const char *ndomain = __nis_domain_of (req.ns_name);
 139                           req.ns_name = strdupa (ndomain);
 140                           if (strcmp (req.ns_name, ".") == 0)
 141                             {
 142                               NIS_RES_STATUS (res) = NIS_NAMEUNREACHABLE;
 143                               goto out;
 144                             }
 145
 146                           __nisbind_destroy (&bptr);
 147                           nis_free_directory (dir);
 148                           dir = NULL;
 149                           status = __prepare_niscall (req.ns_name, &dir,
 150                                                       &bptr, flags);
 151                           if (__glibc_unlikely (status != NIS_SUCCESS))
 152                             {
 153                               NIS_RES_STATUS (res) = status;
 154                               goto out;
 155                             }
 156                           goto again;
 157                         }
 158
 159                     while (__nisbind_connect (&bptr) != NIS_SUCCESS)
 160                       {
 161                         if (__nisbind_next (&bptr) != NIS_SUCCESS)
 162                           {
 163                             nis_free_directory (dir);
 164                             goto out;
 165                           }
 166                       }
 167                     goto again;
 168                   }
 169               break;
 170             }
 171           link_first_try = 0; /* Set it back */
 172         }
 173       while ((flags & HARD_LOOKUP) && status == NIS_RPCERROR);
 174
 175       __nisbind_destroy (&bptr);
 176       nis_free_directory (dir);
 177
 178       if (status != NIS_SUCCESS)
 179         {
 180           NIS_RES_STATUS (res) = status;
 181           goto out;
 182         }
 183
 184       switch (NIS_RES_STATUS (res))
 185         {
 186         case NIS_PARTIAL:
 187         case NIS_SUCCESS:
 188         case NIS_S_SUCCESS:
 189         case NIS_LINKNAMEERROR: /* We follow to max links */
 190         case NIS_UNAVAIL: /* NIS+ is not installed, or all servers are down */
 191           ++done;
 192           break;
 193         default:
 194           /* Try the next domainname if we don't follow a link */
 195           if (count_links)
 196             {
 197               free (req.ns_name);
 198               NIS_RES_STATUS (res) = NIS_LINKNAMEERROR;
 199               ++done;
 200               break;
 201             }
 202           ++name_nr;
 203           if (names[name_nr] == NULL)
 204             {
 205               ++done;
 206               break;
 207             }
 208           req.ns_name = names[name_nr];
 209           break;
 210         }
 211     }
 212
 213  out:
 214   if (names != namebuf)
 215     nis_freenames (names);
 216
 217   return res;
 218 }
 219 libnsl_hidden_nolink_def (nis_lookup, GLIBC_2_1)